1. Field of the Invention
The present invention relates to an electronic apparatus, and more specifically, to an electronic apparatus having circuit boards and high load parts that generate heat, arranged in a casing.
2. Description of the Related Art
With recent electronic apparatuses becoming multifunctionized and more compact in size, there is a general tendency that a plurality of circuit boards, a power source, and expansion cards are packed into a casing of an electronic apparatus having a limited space. In such an electronic apparatus, hot air generated by the power source or electronic parts is blocked by, for example, a plurality of circuit boards which are closely stacked one upon another, to be confined within the casing, so that the electronic parts in the casing become excessively hot. This poses a problem that some electronic parts malfunction or become defective and hence cannot maintain their required performance.
To avoid this problem, as means for discharging heat generated in the casing to the outside of the electronic apparatus, a fan or a heat sink has been provided in the casing. However, multifunctionalization and speedup of electronic apparatuses increase the amount of heat generated in the electronic parts. This leads to increased cases where the fan or heat sink is insufficient to ventilate the interior of the casing in which the plurality of circuit boards and electronic parts are clustered. Thus, there is demand for a cooling structure for the electronic apparatus which can achieve high cooling efficiency.
For example, Japanese Laid-Open Patent Publication (Kokai) No. 2000-049482 discloses a cooling structure for electronic apparatuses which is comprised of a plurality of fans that blow uniform air flows between a plurality of circuit boards mounted in stages in the casing, and guide vanes that guide the uniform air flows.
However, with the disclosed cooling structure for electronic apparatuses, fans are provided between adjacent circuit boards, and therefore, the following problems arise: 1) The number of fans increases; 2) Costs increase; 3) The size of the casing increases; and 4) The fan themselves generate increased heat and noise.